1. Field of the Invention
The present invention relates to an integrating device for integrating a running distance of a vehicle. More particularly, the present invention relates to an integrating device for displaying an integrated value obtained when only a running distance after the delivery of a vehicle is integrated.
2. Description of the Related Art
Usually, an odometer, which is an integrating device for integrating a running distance of a vehicle, is incorporated into a vehicle such as an automobile. In an electronic type odometer, an integrated value of a running distance is stored in a non-volatile memory such as EEPROM.
In the case where the integrated value is stored in the non-volatile memory, this integrated value is set at 0 km (kilometer) in many cases when the odometer is delivered. In this case, in the final manufacturing process of the odometer, a pseudo pulse signal is inputted into the odometer instead of a pulse signal to be detected synchronously with the rotation of an axle, and it is inspected whether or not an appropriate integrated running distance is displayed on the odometer in accordance with the number of input pulses. Further, a running test is conducted by a car manufacturer on a vehicle into which the odometer is incorporated.
However, when the integrated value is set at 0 km in the delivery of the odometer, the following problem may be encountered. As described above, the running test is conducted by a car manufacturer on the vehicle into which the odometer is incorporated. Therefore, when the vehicle is delivered to a user, the integrated value is not 0 km. Accordingly, it is difficult to display an actual running distance of the user on the odometer. In order to avoid the above problems in which the integrated value is increased by various tests conducted on the vehicle, for example, it is possible to take countermeasure in which the integrated value is set at a negative value. However, in the electronic odometer, from the viewpoint of structure, it is difficult to design it in such a manner that the integrated value can be preset at a negative value.
As another method of displaying the actual integrated running distance of a user, there is provided a method in which the odometer is equipped with a function of resetting the integrated value at 0 km after the completion of the test. Therefore, as disclosed in Japanese Unexamined Patent Publication No. 6-241825, they developed an odometer having a reset mechanism by which contents of the non-volatile memory can be reset.
FIG. 4 is an arrangement view showing an odometer which is the conventional integrating device. In FIG. 4, reference numeral 101 is a distance sensor for generating a pulse signal at each predetermined running distance being linked with an axle of a vehicle. In this connection, as the frequency of this pulse signal is proportional to a vehicle speed, it is possible to use the output signal as a vehicle speed pulse. Reference numeral 102 is an arithmetic processing section. This arithmetic processing section 102 includes: a distance arithmetic means 121 for calculating a running distance of a vehicle by counting the number of pulse signals supplied from the distance sensor 101; and a control means for sending and transmitting an integrated value and others among the distance arithmetic means 121, the non-volatile memory 2 and the driver 3 arranged in the display section 104.
Reference numeral 2 is a non-volatile memory such as EEPROM for which no power source for backup is required. Reference numeral 104 is a display section, which includes: a display unit 4 for displaying an integrated running distance by utilizing a liquid crystal or a fluorescent tube; and a driver 3 for controlling the display unit 4.
Reference numeral 105 is a reset control means. The reset control means 105 resets contents of memory stored in the non-volatile memory 2 when a reset input signal is supplied by the reset mechanism 106 such as a reset input terminal arranged in a portion on a circuit substrate used for the odometer.
Next, operation will be explained as follows.
When an ignition switch is turned on and electric power is supplied, the control means 122 in the arithmetic processing section reads out an integrated value of a running distance stored in the non-volatile memory 2 and presets the integrated value in the distance arithmetic means 121. By the distance arithmetic means 121, a distance corresponding to the pulse signal supplied from the distance sensor 101 is successively integrated to the integrated value in the distance arithmetic means 121. At the same time, by the distance arithmetic means 121, an integrated value to which a new distance is integrated is outputted to the control means 122.
The control means 122 outputs the value to the driver 3 in the display section 104. At the same time, the value is stored as a new integrated value in the non-volatile memory 2, so that the integrated value is updated. The driver 3 in the display section 104 displays a value, which is supplied from the control means 122, on the display unit 4.
In this connection, the non-volatile memory 2 continues to hold its memory contents even after the power source is turned off. Therefore, when the power source is turned on next time, it is possible for the control means 122 to read out the integrated value stored last time.
In this way, the integrated value is calculated and stored in the non-volatile memory appropriately.
On the other hand, when a predetermined signal is sent from the reset mechanism 106 to the reset control mechanism 105, it is possible to reset the memory contents (integrated value) of the non-volatile memory 2 and set the integrated value at 0. When the reset control means 105 and the reset mechanism 106 are arranged as described above, the integrated value can be set at 0, for example, after the test running has been completed. Due to the foregoing, it becomes possible to display the integrated value of an actual running distance after the vehicle has been delivered to a user.
Since the conventional integrating device is composed as described above, the following problems may be encountered. There is a possibility of an unfair operation such as reducing the integrated value of the running distance conducted by a user when the user operates the reset mechanism 106. Accordingly, it becomes difficult to find a precise running distance of a vehicle.
In this connection, it is possible to employ an arrangement of the odometer in which the reset mechanism 106 is arranged in a portion on the circuit substrate of the odometer so that it becomes difficult to recognize the existence of the reset mechanism 106 in the appearance of the odometer. However, even if the above arrangement is adopted, when a user finds out the existence of the reset mechanism 106, the integrated running distance is changed by the user, for example, when the odometer is detached from the vehicle and the reset mechanism 106 is operated by the user. Further, it is possible to employ an arrangement of the odometer in which the reset mechanism 106 is composed of a plurality of switches and the operation of the reset switches are encoded by utilizing a combination of ON/OFF of the switches. However, this arrangement has the following disadvantages. When the number of switches is increased, the size of the apparatus is necessarily increased. When the number of switches is decreased, operation of the reset switches is easily decoded.
Further, the following problems may be encountered in the conventional integrating device. It is possible to consider that when the integrated value has reached a previously determined maximum value (for example, 999,999 km), the integrated value is returned to 0 in the next counting operation. In this case, there is a possibility of an unfair operation in which the integrated running distance is made to reach the maximum value again so that the integrated running distance can be returned to 0.